Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
What you've asked is a good question. I don't have an answer to that. I chose to solve the question as proposed before your answer because it requires a bit more from the coder, in this case, me.
Fair play, that is more elegant. As a question, why allow negative prices or servings?